The end of the American Revolution left the task of rebuilding Great Cow Harbor to just thirty-one families. Farms were replanted, sheep and cattle were replenished, and the residents looked at the sea and saw the future. The second lighthouse built in the United States was erected at Eaton's Neck in 1798. Four years later, twenty-eight residents petitioned the Town of Huntington for a public dock at Bryant's Landing - now the Northport Village Dock.

The harbor took on one of its most important roles - and began to take its present-day shape - during the War of 1812, when shipyards began to appear along Bayview Avenue. By 1840 shipbuilding had become the community's first major industry. Its most successful shipbuilder was Jesse Carll, who in 1855 set up shop at the intersection of Bayview Avenue and Main Street, site of the current village park. Carll remained the leading shipbuilder in Northport until 1890; his son Jesse continued to run the yard until 1918. Ultimately, Northport turned out more than 200 sailing vessels by the time the industry waned in the late 1800s, when steel hulls, for which the local yards were unsuited, began to replace wood, and improved roads diminished the need for coastal trading vessels.

By the 1830's the name Northport was beginning to replace Cow Harbor, and shipbuilding had become a major industry. The famous schooner "Jesse Carll" was built in 1867 and launched on Long Island Sound. After reaching Boston, the "Jesse Carll" set out for the continent and succeeded in setting a new transatlantic sailing record. Meanwhile, the residents were also going places by land. A stage coach operated by George Wheeler's Livery met the trains at 25-A and Church Street from 1873 to 1887 and then at the East Northport station.

In 1887, the American and English Encyclopedia of Law was copyrighted, and subsequently published at the Edward Thompson Building erected at the corner of Woodbine and Scudder Avenues. The Thompson Law Book Company, which drew an influx of lawyers to the community, was acquired by West Publishing Company. This imposing brick structure has been recently restored as "The Promenade" and houses a variety of shops and offices.

The Village of Northport was incorporated in 1896 and the Northport Electric Light Company was founded. Northport was the first village in Huntington Township to convert to electricity, and in 1902, the electrically-operated Northport Trolley line relieved horses of the chore of meeting trains. Buses were introduced to Northport in 1924. In 1911, Northport Electric merged with lighting companies from neighboring communities to form the giant once known as Long Island Lighting Company (LILCO), now known as LIPA and KeySpan. Meanwhile, Northport had made a cultural advance with the establishment of the Union Opera House of Union Place.

The late 19th Century brought ferries from New York City and an increase in visitors that filled boarding houses built earlier in the century. But it was another maritime trade, one that survives today, that came to dominate the harbor. Shellfishing developed in 1848 when oyster beds were discovered in Northport Bay. The catch was processed on docks along Bayview Avenue. By the turn of the century, oystermen had banded together to form Long Island Oyster Farms Inc., which survived until 1990.

In 1881, Edward Thompson, who had been a successful oysterman, and James Cockcroft established the Edward Thompson Law Book Co., which eventually was housed in a large brick building at the corner of Woodbine and Scudder Avenues. The Thompson firm published the country's first legal encyclopedia and its law books were shipped around the world. The company moved to Brooklyn in the 1930s, but not before its staff of lawyers had a major impact on the village's development into a modern community. In 1894, the law-book people led the drive that made Northport the first incorporated village in the Town of Huntington; they also developed its fire department, the public library - an original Andrew Carnegie library, in 1914 - and a debating society.

In 1895, the Thompson principals brought electricity to the community. They started the Northport Electric Light Co., which built a steam-powered plant where Cow Harbor Park is located now. In 1911, the Northport utility along with ones in Islip, Amityville and Sayville merged to form Long Island Lighting Co.

One industry tied to the harbor that wore out its welcome was sand mining. In the 1950s residents battled the Steers Sand and Gravel Co., which had been operating in the village since 1923, about the company's removal of the sand and gravel from the foot of Steers Avenue. The sand pit was halted just short of Ocean Avenue, and ``the pit,'' as locals still refer to it, became a housing development.

In 1867, when the Long Island Rail Road was extended from Syosset to Northport, a station was established in the village, near where the King Kullen shopping center is now. It lasted only six years, however: In 1873 the station was moved to East Northport. An electric trolley ran from the business district to the train station from 1902 to 1924, and some of the tracks remain. A horse-drawn trolley operated in the '70s and '80s as a weekend tourist attraction.